1. Field of the Invention
The present invention relates to a laser processing method of splitting laser to be used in processing into multiple beams and irradiating a surface of an object with the beams, and a laser processing apparatus for enabling the laser processing method.
2. Related Background Art
In a technology of irradiating a workpiece with laser light to process the workpiece, the beam quality of the laser light is extremely important. For example, where the laser light is condensed to increase the beam intensity in a light condensing spot, the laser light preferably has the beam quality M2 close to the diffraction limit capable of narrowing the light condensing spot to a high density. Namely, it is desirable that the beam quality M2 be nearly 1. The laser light with the beam quality M2 of nearly 1 in this manner is suitable, particularly, for removal processing such as boring or cutting.
On the other hand, where a joining processing is performed by a laser light irradiation, the laser light must be irradiated simultaneously onto two or more workpieces. For this reason, it is unpreferable that the light condensing spot be limited to a too narrow region. Instead, it is desirable that a beam intensity distribution in an irradiated region be a flat-topped homogeneous distribution. A homogenizer including a diffractive optical element, for example, as disclosed in Japanese Patent Application Laid-Open No. 2003-114400, is proposed as a technology to meet such a demand.